The present invention relates to systems for and methods of characterizing aerosol spray plumes, more particularly, to systems and methods that illuminate an aerosol spray plume and utilize optical techniques to characterize the plume.
A pulmonary delivery route is preferred for medicines used in the treatment of many pulmonary diseases and respiratory ailments because the dose of medication can be delivered to tissues that can more efficiently absorb the medication, thereby more readily bringing relief to patients. In addition, medications for non-respiratory problems such as flu vaccines, insulin and migraine relievers can also be delivered with an aerosol delivery system (ADS). However, patients with different medical conditions present challenges respecting the safety and efficacy of the aerosol delivery system, in part due to the different physical properties of the different formulations for different medications. The fluid dynamic characterization of the aerosol spray of a particular medicine emitted by a metered nasal spray device is therefore crucial in determining the overall performance of the inhaler as a drug delivery device.
Spray plume characterization is an integral part of the regulatory submissions necessary for Food and Drug Administration approval. The plume acts as a quick and precise indication of the overall performance of most ADS. Most importantly, drug targeting can be optimized by the appropriate choice of aerosol delivery system and formulation. Further, studies of characteristics of spray plumes from different ADSs can be used to guide product design.
One approach to spray plume characterisation is described in WO 01/13092 of Image Therm Engineering published Feb. 22, 2001. In the described system, a laser generates a fan-shaped sheet of light which is aligned with, and passes through, the spray axis of a spray plume in order to illuminate a slice of the plume along the spray axis. A digital camera positioned to a side of the plume captures consecutive images of the slice.
The laser is then adjusted to generate a fan-shaped sheet of light which is transverse to the spray axis in order to illuminate a transverse cross-sectional slice of a spray plume. The digital camera is re-positioned to a position above the plume to capture consecutive images of the transverse plume slice.
While this system provides characteristics of the plume, the plume is not fully characterised and it would be advantageous to have a system which provided fuller information on the characteristics of the plume.
The density of a spray plume generated by an aerosol delivery system (xe2x80x9cADSxe2x80x9d) may be characterised by illuminating a face of the plume with light and then imaging the plume. The shape of the plume may be characterised by operating the ADS in a controlled manner to form a first spray plume. A face of the plume is illuminated and the plume imaged from a first side parallel to the spray axis of the plume. The ADS is then again operated in the controlled manner to form a second spray plume. A face of the second plume is illuminated and the second plume imaged from a second side which is parallel to the spray axis of the plume and perpendicular to the first side.
According to the present invention, there is provided a method of characterising a spray plume, comprising: illuminating a spray plume with light such that said light impinges upon the entirety of a first side of said spray plume; imaging said illuminated spray plume from a second side perpendicular to said first side.
According to another aspect of the invention, there is provide a method of characterising a spray plume, comprising: operating an aerosol delivery system in a controlled manner to form a first spray plume; illuminating said first spray plume with light such that said light impinges upon the entirety of a face of said first spray plume; imaging said first spray plume from a first side parallel to a spray axis of said spray plume; operating said aerosol delivery system in said controlled manner to form a second spray plume; illuminating said second spray plume with light such that said light impinges upon the entirety of a face of said second spray plume; imaging said second spray plume from a second side parallel to a spray axis of said spray plume, said second side being perpendicular to said first side.
According to a further aspect of the invention, there is provided a system for spray plume characterisation, comprising: a source of non-coherent illumination positioned for illuminating a spray plume with light such that said light impinges upon the entirety of a first side of said spray plume; an imaging device camera for imaging said illuminated spray plume from a second side perpendicular to said first side.
According to another aspect of the invention, there is provided a system of characterising a spray plume, comprising: an actuator for operating an aerosol delivery system in a controlled manner to form a spray plume; a source of illumination for illuminating said spray plume with light such that said light impinges upon the entirety of a face of said spray plume; an imaging device positioned for imaging said spray plume from a side parallel to a spray axis of said spray plume; a turntable having a rotational axis parallel to said spray axis for rotating said aerosol delivery system.
According to a further aspect of the invention, there is provided a system of characterising a spray plume, comprising: means for operating an aerosol delivery system in a controlled manner to form a first spray plume and, subsequently, a second spray plume; means for illuminating said first spray plume with light such that said light impinges upon the entirety of a face of said first spray plume and for illuminating said second spray plume with light such that said light impinges upon the entirety of a face of said second spray plume; and means for imaging said first spray plume from a first side parallel to a spray axis of said spray plume and for imaging said second spray plume from a second side parallel to a spray axis of said spray plume, said second side being perpendicular to said first side.